1. ${L}_{1}$and ${L}_{2}$ are two straight lines.
The origin of the coordinate axes is $O$.

${L}_{1}$ has equation $5x+10y=8$
${L}_{2}$ is perpendicular to ${L}_{1}$ and passes through the point with coordinates (8, 6)

${L}_{2}$ crosses the $x$-axis at the point $A$.
${L}_{2}$ intersects the straight line with equation $x=–3$ at the point $B$.

Find the area of triangle $AOB$.
Show your working clearly.